Method of impregnating fibrous materials



April 2l, 1942.

W. B. CAMPBELL ETAL METHOD'OF IMPREGNATING FIBROUS MATERIALS Filed May 5, 1939 v 3 m W m w m I M? N L W L S w a 0 mwm N T mmk m A 1w mmmw fl \om ms wgA mm 5 M s m ma w m a w.

Patented Apr; 21 1942 I UNITED. STATES PAT E'N'T OFFICE METHOD or IMPREGNATING ruinous MATERIALS William Boyd Campbell, Montreal, Quebec, om

Maass, Westmount, Quebec, and Ernest Edward wMassey,

Montreal, Quebec, Canada, assiguors to-Imperial Tobacco Company of Canada, Limited, Montreal, Quebec,

Application May 5, 1939, Serial No. 271,950

4 Claims.

This invention relates a method and apparatus for impregnating paper or other material, in

the form of rolls or stacks, with wax or other I organic or inorganic solids capable of being dissolved ina solvent that will not adversely affect the rolled or stacked material.

The principal object isto enable the wax or other impregnation of paper or other material, in

the form of rolls-or stacks, to be effected under -"conditions favorable to the'uniform application of the impregnating material and to the maximum recovery of the solvent or solvents con- 'tained in the treating solution.

In treating rolls or stacks of paper in accordance with this invention it is important that the wax or other solids to be incorporated in or apfrom the following detail description taken in connection with the accompanying drawing, in which the single figure is a diagrammatic illustration of one form of apparatus which m'ay be used in carrying the invention into eilect.

Referring more particularly tothe drawing 5 designates a vacuum tank in which paper or other fibrous material is treated in accordance with this invention. The treating solution is preferably prepared in. the solution tank 6 by introducing the necessary ingredients through valve I. Alternately, the treating solution may be prepared in a separate mixing vessel and then introduced into tank 6- through said valve. When the apparatus is in use the treating solution is passed from tank 6 to tank 5 and viceversa Canada In putting the apparatus into operation the tank 5 is loaded with the material to be treated and the treating solutionii's prepared in or introduced into tank 6. At this time valves 1, 16, ll, l2c and l2d are open but valves 2|, 22 and 9 are closed. Tank 5 is thus placed under vacuum to establish a desired absolute pressure therein. Valves I6, I and l2'd are now closed and valve 9 is opened, Since tank 6 is under atmospheric f pressure (the valve 1 being still open) the solution contained therein is forced into vacuum tank 5 through line 8 and valve 9. When this trans-.

fer is completed valve 9 is closed and the fibrous material in tank 5 is allowed to soak in the treating solution for a suitable period. During this soaking period tank 5 is gradually heated, by

heating coil 29, to a temperature above the boiling point of the solvent contained in the treating 3 solution. Owing to resulting vaporization of the solvent contained in the treating solution the pressure in tank 5 becomes greater than that in tank 6 which is at atmospheric pressure. After thefibrous material has thus been soaked in tank 5 for the desired period, valve 9 is opened. T

Owing to the diflerence in pressure in the two tanks the treating solution is now returned to tank 6 through line 8 and valve 9. When this transfer oi the solution from tank 5 to tank't is completed the valve 9 is again closed.

solvent from the impregnated material. To this end a vacuum is drawn on tank 20, coil I3 and line I2 by opening valves I6, I 1, 2|, 22 and l 2 c while valves l2b and l2d are closed. When the in tank '20, coil l3 and line l2, valves I 6 and I! are closed and valve |2d is opened. At this time water from a. cooling tower or other source -is circulated through the condensing tank H by through line tand valvaflx'lfhe upper portion 401 opening valve 25 in the water supply line 26 and of tank '5 is connected, througl'i'liiie 12 to one l5 is provided with valves I2 and I1. Line l5 5 are also connected through bypass line 12a equipped with a valve l2b. Line I2 is equipped with valves I 20 and I2d, the former being located between the bypass connection 12a and the coil 13 and the latter being located adjacent tank 5.

valve 21 m the drain line 28. With this particu- The next step is to evaporate, and reclaim the desired vacuum conditions are thus established lar setting of the valves (valves I6, I! and l2b being closed and valves open) the solvent evaporated from the material in tank 5 is drawn into the solvent tank through valves 12d, line l2; valve I2c, condensing coil I3,

line l9 and valve22. The lat, traces of solvent are then removed'from tank'l b'yclosing valve I20 and opening'valve H17 in pipe bypass line l2a.

'I'heentire procedure described inthe fore- :going is repeated one or more times before the material under treatment is removed from tank 5. We find that this repetition of treatment is usually necessary to obtain the best results.

During both the. impregnation and solvent re- 2l, 22, He and IM being 2 covery periods tank l is heated by passing steam through the previously mentioned heating coil as which is contained in a water jacket I. surrounding the treatment chamber la. Tank i may also be provided with a central hollow tubular member 3| rising from the bottom of the tank and communicating with the water jacket to. This member .tl extends upwardly at the centre of the fibrous material being treated and provides additional surface to assist in ei'iecting uni: form distribution of the heat derived. from coil 29. Tank 8 is also preferably provided with a water jacket 32 containing a heating coil it through which steam or other heating agents is passed.

The heatingof tanks and C may be automatically regulated with the aid of suitable thermostats t4 and SI. These thermostats are arranged in the lower portions of the tank and may be connected in any suitable manner to indicate and/or regulate the steam heating of the tanks.

In one instance in which the invention was used for the production of wax impregnated cigarette paper the treating solution was composed of the following ingredients mixed together in the following proportions, by weight:

. Pounds Carbon tetrachloride 150 Beeswax 2 Carnauba w 1% Ins preparing; this solution the waxes were melted and poured into the solvent whichhas previously been heated to 45 to 50' C. The mixture was then stirred to ensure complete solution. When any appreciable interval of time is permitted to elapsebetween the preparation and use of the solution it isusually necessary to reheat the solution to 45 C, since some wax may separate from the solution during such interval.

. While we have described what is now considered to be a preferred embodiment of this invention it will be understood that various modifications may be resorted to in practice. For example. the

various control valves may be operated either manually or automatically and through the agency of any desired operating mechanism.

Having thus described our invention, what we claim is;

l. The herein described method of impreI- nating fibrous material in the form of rolls or stacks with a treating solution comprising solids dissolved in a volatile solventwhich comprises (i) placing said material in a vacuum tank, (2) introducing the treating solution into said tank} (3) permitting said material to soak in the treating solution for a predetermined period during which the tankis gradually heated to a temperature above the boiling point of the solvent contained in the treating solution, (4) withdrawing residual treating solution from the tank atthe end of the soaking period and (5) withdrawing the evaporated solvent from said tank while continuing the heating of the latter to evaporate the. solvent absorbed by thematerial I placing the treating chamber in communication treating solution into a storage tank which is always under atmospheric pressure; (2) placing the rolls or stacks in a treating chamber: (3).

with a source of suction and then disrupting said communication when a predetermined subatmospheric pressure is established in said chamher; (4) placing the evacuated treating chamber in communication with the storage chamber whereby the treating solution is transferred from 'the storage chamber to the treating chamber by atmospheric pressure; (5) disrupting the communication between said chambers when the transfer of the treating solution is completed;

(6) permitting the rolls or stacks to soak in the treating solution for a suitable period while heating the treating chamber to a temperature above the boiling point of the solvent contained in the treating solution; (7) re-establishing'communication between the treating chamber and the storage chamber whereby the unabsorbed treating solution is forced back to the storage chamber by the pressure or the evaporated solvent contained in the treating chamber; (8) disrupting communication between said chambers when the transfer of th treating solution from the treating chamber to the storage chamber is completed; (9) removing all solvent fromthe treating chamber and from the treated material by exhausting the evaporated solvent from said chamber while simultaneously heating said chamber (to a temperature above the boiling point of the solvent, and (10) repeating steps 4 to 9 (2) to (5) inclusive be inclusive before removing the material from the I treating chamber. 3. The method of impregnating rolls or stacks of paper with a treating solution consisting of solids dissolved in a volatile solvent which comprises subjecting the rolls or stacks to successive soakings in said solution with intermediate removal or the solvent from the paper by the applicatlon of heat and suction, the soakingsbeing carried out at a temperature above the boiling point of the solvent contained in said solution.

w. norm caurnnm.

a. EDWARD MASSEY.

4. The method of impregnating paper is the 

